[ubuntu] Old proxy info - no network config manager

http://ubuntuforums.org –
I am having trouble removing some old proxy information, I am also having trouble getting network config manager to come up. A while ago something happened and I had to manually edit /network/interfaces. I guess I am looking for a way to default my network settings back to it was from an original install.
(Hardware)

I'm trying to use a proxy with Chromium (25.0.1364.160 on Kubuntu 13.04) but whatever settings I use Chromium ignores. The proxy is configured and working correctly and confirmed to be working by using Firefox.

Here's what I've tried:
Quitting Chromium and setting the system wide proxy using System Settings->Network Settings->Proxy.